Method of improving the adsorbent and decolorizing properties of georgia-florida fuller&#39;s earth



Patented July 26, 1 949 METHOD OF IMPROVING THE ADSORBENT ANDDECOLORIZING PROPERTIES OF GEORGIA-FLORIDA FULLERS EARTH William S. W.McCarter, Ardmore, Pa., assignor to Attapulgus Clay Company,Philadelphia, Pa., a corporation of Delaware No Drawing. ApplicationAugust 21, 1948, Serial No. 45,572

10 Claims. 1

The present invention relates to a process for improving thedecolorizing efiiciency of Georgia- Florida type fullers earth, andrelates more particularly to increase the effective life of such earthupon repeated use and regeneration in the field of oil decolorizationand refining.

It has been known heretofore that the decolorizing efl'iciency ofGeorgia-Florida type fullers earth may be substantially increased uponboth a Weight and. volume basis by mixing with raw fullers earth a smallamount of a water-soluble alkaline reagent and suflicient water torender the earth plastic, extruding the mixture at an elevated pressure,drying the extruded earth, reducing the dried earth to granularparticles, and calcining the granular particles at 800 F. to 1200 F.Such process is disclosed and claimed in United States Patent 2,363,876to W. A. La- Lande, Jr.

In utilizing fullers earth for the treatment of petroleum products,especially for the decolorization of lubricating oils, petrolatum, andwaxes, it is the practice to percolate the petroleum fraction throughthermally activated fullers earth until the desired degree of refiningor decolorization is no longer obtained. It is not feasible,economically, to discard the used earth at this point. Instead, theearth must be treated to restore its adsorptive properties for reuse.This regenerative treatment usually involves washing the spent earthwith a solvent such as naphtha, purging the washed spent earth withsteam, drying the steamed earth, and calcining or burning the driedearth in the presence of air to oxidize and remove strongly adsorbedtars, asphalts, and other carbonaceous matter.

I have found that under this regenerative treatment, the fullers earthcontaining the added alkaline reagent produced according to the La-.Lande process aforementioned, rapidly deteriorates in decolorizing or'adsorptive efiiciency. I have also found, however, that thisdeterioration in efliciency can be decreased substantially, without anyeffect upon the beneficial action of the alkaline reagent, byneutralizing the alkaline reagent at any oneof several stages during thepreparation of the improved earth following the initial mixing orimpregnation of the earth with the alkaline reagent. The neutralizationis effected using a mineral acid, preferably diluted with water if theinitial acid was concentrated. Acids such as sulfuric, hydrochloric,nitric, .phosphoric, or hydrofluoric may be used, preference being hadfor sulfuric acid due to its availability, cheapness, and relative easeof handling. The amount of acid used is only that necessary toneutralize the alkaline reagent originally incorporated in the earth,since amounts greater than the stoichiometric equivalent are notbeneficial and, in fact, may have an adverse effect upon the earth. As amatter of fact, it is well known that Georgia-Florida fullers earth isnot improved by conventional acid activation as practiced withmontmorillonite sub-bentonites, and fullers earth from the vicinity ofAttapulgus, Georgia, is actually harmed by acid leaching (U. S. Dept.Interior, Geol. Survey #3 (1933) pages 45-49). It is, therefore,emphasized that the neutraliza tion of the fullers earth containingadded alkaline reagent, in accordance with this invention, is not anacid activating treatment and is not to be confused therewith.

In carrying out this invention, the amount of alkaline reagent initiallyincorporated in the fullers earth must be held within the range of 0.1%to 1.75% by weight, based upon the dry or volatile-tree earth, otherwisethe adsorbent or decolorizing eificiency is adversely affected, eventhough the alkalized earth is subsequently neutrailized with mineralacid. It is preferred to use from about 0.75% to 1.50% of alkalinereagent, about 1% of a reagent such as sodium hydroxide giving excellentresults. Among the reagents reacting alkaline in aqueous solution whichmay be employed in accordance with this invention are the oxides,hydroxides, peroxides, carbonates, bicarbonates, secondary and tertiaryphosphates, and silicates of Na, K, Li, and NH4 which are soluble inwater to substantial extent. Due to their availability, effectiveness,and non-corrosive properties, the alkali metal hydroxides, andparticularly sodium hydroxide, are preferred. Other alkaline reactingsubstances which may be employed are the alkoxide and phenolates ofstrong bases; soluble magnesium, calcium, and barium salts of weakacids; alkali metal aluminates, zincates, plumbites, arsenites,aresenates, antimonoites, stannites, stalnnates chromites, manganates,and phosphites; amides of metals forming soluble strong bases,quaternary bases such as tetralkyl ammonium hydroxides, tetrarylammonium hydroxides, and mixed alkaryl ammonium hydroxides; hydrazine,hydroxylamine, and other soluble organic bases.

In accordance with the present invention, raw

fullers earth of the type obtained from the Georgia-Florida fullersearth deposits and containing natural moisture (40% to 50% by weight) ispassed to a roll crusher wherein the lumpy earth isreduced to relativelyfiat fragments. The earth from the crusher is introduced into aconventional pug mill in which the earth isintimately mixed with thealkaline reagent in aqueous solution, the quantity of agent being of theorder or 0.1% to 1.75% by weight, .fba'sed upon volatilefree earth, andpreferably "about 1% by .weight. Depending upon the initial moisturecontent of the raw earth, the concentration ,of the alkaline solution isadjusted to give ,atoital volatile-matter content (V. M.) in the earthof the order of 45% to 60% by weight, and preferably 52% to 56% byweight. The plastic, alkalized earth may then be subjected to any of thefollowing procedures involving neutralizing and converting-the earthinto an improved adsorbent and decolorizingaeent.

For example, the plastic earth containing 1% of sodium hydroxide and 54%volatile content (water) was mixed with sufficient dilute sulfuric acidconcentration) onlyto neutralize .the added alkali, .the neutralizedearth was washed with :Water to remove .the soluble salts .formed, andthe washed earth was dried .to 5.4% -.volatile content. This earth .wasthen extruded through an auger extrusion .machinehavinga 2 inch diameteraugerand a barrel 1.4 .inches in length ;-provided at thedischargeend-with a die ,pl-ate linch thick containing a plurality .ofM; inch diameter apertures. Extrusion was accomplished at .a

fairly high pressure, 1. .e., above 100 pounds per sp uare :in-oh, theusual pressure range being of the order of 400 to .1200 ,pounds .persquare .inch. The moist, extruded earth discharged from the die plateapertures wasdried at 250 F. to 300 F. to avolatilecontent ofabout 1.5%.by weight. The dried earth was then reduced to granular .particles bygrinding, and the resulting particles .of desired size, for example,.30-60 mesh were .calcined at 900 F. for minutes, and the calcinedproduct was screened to remove particles finer than .50 mesh. The.calcination step may .be performed at any temperature within the range.of 800 F. to 1200 ,F., and the particle size may be varied as desired.

The .decolor-izing eificiency of the improved i-uller s earth wasdetermined by solution filtration of Pennsylvania cylinder oil stock 60%.by

volume naphtha-% by volume cylinder stock) through a given weight ofearth at 135 F. to 6 N. P. A. color. The volume of filtrate of -6 N. P.A. color thus obtained, when compared with the volume of filtrate of.the same color obtained by liltration through commercial f-ullersearth, is indicative 0f the decolorizing efiiciency of the improyedearth. Commercial iullers earth isobtained by drying raw Georgia-Floridaearth, grinding, screening to 30-60 mesh, calcining at 900 F., andremoving particles finer than .60 mesh by rescreening. The weightefiicien-cy and volume efliciency upon the first use of commercialiullers earth is arbitrarily designated 100%. To determine efficiencyupon repeated use and regeneration of the improved earth, the used im'-proved earth was drained of oil, washed with naphtha, steamed and airblown, and finally re- Number of Uses 1 2 3 4 5 6 v. M., per cent 3 .0;2;0 1.}9 1. '9 1.9 2.0 Vol. Wt.,1bs./cu.ft 31.1 31.6 32.6 33.1 33.4 33.8Wt. efficiency, per cent"... 131 136 141 141 136 Vol. eificiency, percent... 127 133 134 144 142 137 In the "above example, neutralization ofthe "earth waseirectedimmediately after the thorough incorporationo'f'the alkaline reagent in the earth. :However, the samebeneficialresults may be ob- .tained by neutralization after extrusion, as isiilustrateii below.

For example, 1% of sodium hydroxide and sufficient water to give 54%volatile matter content was added to raw fullers earth in a pug mill andthe mixture was thoroughly milled. The resulting plastic, alkalizedearth was then extruded as in ;the first example, and the extruded e'art-h "was then treated with :dilute .sulfuric acid in an amountchemically equivalent to tiresalkali Iinitially added. Following :theneutralization, the

earth was waterwashedfto remove soluble :salts,

Number of Uses i. l r 2 f 3 i 5 '-6 V.M.,per-c'ent 3.1 251 9 17- 15s asWt. efiiciency per cent- 139 141 138 154 Volvefliciency,per eenth"; 134145 149 1 H45 146 =l44 In Example 2, neutralization was efiect'ed a fterextrusion, and a second extrusion was required, since the initial-'extrud'ate disintegrated into fines during the neutralization. inanother modification of this invention, 1% of sodium hydroxideandsufii'cient water to give 54% volatile -content was added to rawfull-ers earth in 'a'pug mill "and the mixture was thoroughly milled.The resulting plastic, alkalized earth was then extruded'as in the firstexample, and the extruded 'earth was dried and thereafter treated withsufficient sulfuric acid'to neutralize the added alkali. Duringneutralization, the extrudate disintegrated into fines, and thismaterial was water washed to remove soluble salts. The washed earth wasredried to 154% volatile content, again extruded, dried, round, screenedto 30-60 mesh, and calcined at 900 F., the material finer than '60 meshbeing thereafter screened out. The decdroi'ization tests upon thisimproved earth are set forth below, and were carried out as in Example1.

Vol. efiiciency, percent.

.In Example '3, neutralization carried out after the initial extrusionand drying. However, as shown in the following Example 4,,neutralizacined at 900 F. for 30 minutes, and the calcined earth, aftercooling, and removal of particles finer than 60 mesh, was treated withsulfuric acid in an amount sufficient only to neutralize the alkaliinitially added. The neutralized earth was water washed to removesoluble salts and dried at elevated temperature. The tests upon thismaterial are shown in the following table, and were carried out as inExample 1.

Number of Uses 1 2 3 4 5 6 v. M., Percent 2.9 2.2 2. 1.9 1.9 2.0 V0].Wt. lbs/cu. It 34. 4 34. 4 35. 4 35. 35. 5 35. 6 Wt. efliciency, percent135 136 131 125 121 120 Vol. efiiciency, percent- 143 144 145 138 134133 In order to compare the efiiciency .of the lullers earth produced inaccordance with this invention, with alkalized fullers earth of theprior art which has not been neutralized, the following example ispresented. To raw fullers earth was added 1% of sodium hydroxide andsufiicient water to give a volatile content of 54-.%, and the mixturewas thoroughly milled in a pug mill. The resulting plastic earth wasthen extruded as in Example 1 and the extrudedearth was dried, ground,and screened to 30-60 mesh, calcined at 900 F. for 30 minutes, and againscreened toremove particles finer than 60 mesh. In this instance, noneutralization was carried out at any stage of the process. The calcined30-60 mesh earth was then tested for decolorizing efficiency asinExample 1, and the results are given in the following table.

1 It will be noted from the above. that the un-.

neutralized earth, after the 4th use and regeneration, rapidly declinedin both weight and volume efficiency, whereas the earths prepared inaccordance with thisinvention retain a relativelyhigh decolorizingefliciency even after the 6th use and regeneration. Although not shownhere. these earths still retain a high efficiency even through 10 tocycles of use, and the rate of decrease in efliciency is very slow incomparison with unneutralized, alkalized earths.

In carrying out the neutralization step, it is important that onlysufiicient mineral acid be used to react with the alkaline reagentinitially incorporated in the earth. In other words, chemicallyequivalent or stoichiometric amounts of acid are employed, there beingno excess acid which might react with the earth and. cause degradationthereof. The concentration of the acid may vary over a considerablerange, 1. e., 5% to 85 however, it is preferred to use relatively diluteacid, for example, sulfuric acid of 10% to 25% concentration.

To illustrate the effect of an excess amount of acid-in treating thealkalized earth, the following example isgiven. To raw fullers earth wasadded 1% of sodium hydroxide and sufiicient water to give 54% volatilecontent, and the plastic earth was milled and then extruded as describedin Example I. The extruded earth was dried at 750 F. to preventdisintegration in the dilute acid: subsequently employed to neutralizethe earth. The dried earth was ground and screened to 30-60 mesh, andthen divided into two equal parts. One part was neutralizedwith astoichiometric proportion of dilute sulfuric acid, while the second.part was treated with 3 times the stoichiometric proportion of acid. Thetreated earths were then water washed to remove soluble salts, dried,and calcined at 900 F. for 30 minutes, any material finer than 60 meshthen being separated by screening. The earth samples were then tested asdescribed in Example 1, and the sample neutralized with astoichiometricamount of acid. had a volume weight or 32.6 pounds per cubic foot and avolume eificiency of 127%, whereas the sample treated with 3 times thestoichiometric amountof acid had a volume weight of 31.8 and a volumeefliciency of 119.8%. apparent that the use of acid in excess of thatrequiredto effect neutralization is detrimental to the efiiciency of theearth. i

While, in general, it is customary to employ fullers earth of 30-60 meshfor the percolation decolorization of oils, it is of course within thescope of this invention to produce earths of any desired mesh, forexample, 4-8, 10-60, 20-80, or even finely divided earth of 100, 200,300 or finer mesh. In the processing of the earth, it is the usualpractice to simply dry the final product, for example, at 250 F. to 400F. to a volatile matter content of about 15 by weight, and market sameat that volatile content. Prior to use in decolorizing oils or othermaterials, the user generally calcines the product at 800 F. to 1200 F.to a volatile content of 1.5% to 3% by weight. The improved earths ofthis invention may be employed in the decolorization or refining ofhydrocarbon oils, waxes; animal and vegetable oils and fats, and thelike. 1

I claim: I i I 1. In a process for improving the decolorizing efficiencyof Georgia-Florida type fullersearth involving mixing the earth withfrom 0.1% to 1.75% by weight of a water-soluble alkaline rethe extrudedearth,the step which consists intreating the earth with mineral acid inan amount sufficient only to neutralize the added alkaline reagent aftersaid reagent has been thoroughly incorporated in the earth.

2. In a process for improving the decolorizing efi'iciency ofGeorgia-Florida type fullers earth involving mixing the earth with from0.1% to 1.75% by weight of a water-soluble alkaline reagent andsufficient water to give a plastic earth containing from 45% to 60% ofwater, extruding the plastic earth at elevated pressure, and drying theextruded earth, the step which consists in treating the earth withsulfuric acid in an amount stoichiometrically equivalent to the alkalinereagent added, after said reagent has been thoroughly incorporated inthe earth.

3. A process for improving the decolorizing emciency of Georgia-Floridatype fullers earth, which comprises intimately mixing with the earthfrom 0.1% to 1.75% by weight of a water-soluble It is, therefore,

crevasse alkaline reagent and anc ent water to give a plastic earthcontaining from 45% to 60% of water, treating the earth with mineralacid in an amount sufiicient only to neutralize the added alkalinereagent, water washing the treated earth to remove soluble salts,adjusting the water conwater to give a plastic earth containing from 52%to 56% of water, treating the earth, with sulfuric acid in an amountsufficient only to neutralize the added sodium hydroxide, water. washingthe treated earth to remove soluble salts. adjnsting the water contentof the washed eartlg to a value between 52% to 56 %,extruding thewashed:v J

earth at elevated pressure, and drying the extruded earth. l

5. A process for improvin the deicolorizing efficiency ofGeorgia-Floridatype ful'lers earth, which comprises intimately mixingwith the'earth from 0.1% to 1.75% by weight, of a watersolubl'e alkalinereagent and sufficient water to give a plastic earth containing from 45%to 60% of water, extruding the plastic earth at elevated pressure,treating the extruded earth with mineral acid an amount sufficient onlyto neutralize the added. alkaline reagent, water washing the treatedearth to remove soluble salts,- adjusting the water content at thewashed earth toa value between 45% and 60%, extrudingrthe .washed 7earth at elevated pressure,- and drying the extruded earth.

- 6. YA proees for improving the decolorizing efficiency ofGeorgia-Florida type: fullers earth,

which comprises intimately mixing with the earth- 1.%' by weight ofsodium hydroxide and suificient water to give a plastic earth containingfrom 52 to 56% of water, extruding the plastic earth at elevatedpressure, treating the extruded earth with sulfuric acid in an amountsufiicient only to neutralize the added sodium hydroxide, water washingthe treated earth to remove solublesalts, adjusting the water contentofthe washed. earth to a valuebetween 52% to 56%, extruding the washedearth at elevated pressure, and drying the from 0.1% to. 1.75% by weightof a water s'oluble alkaline reagent and suffici'ent water togive aplastic;earth containing from 45% to '60%' of water, extruding theplastic earth at elevated pressure, drying the'extrudedi earth, treatingthe dried earth with mineral acid in an amcunt' sufficient, ronly' toneutralize the added alkaline reagent, water washing the neutralizedearth to remove soluble salts adjusting the water content of the washedearth to a value between 45%- and 60%, extruding the washed earth atelevated pressure, and drying. the extruded earth.

8. A process for improving the decolorizinget ficiency ofGeorgia-Florida type frullers earth, which comprises intimately mixingwith the earth 1% by weight of sodium hydroxide and sufficient water togive a plastic earth containing from 52%- to 56% of water, extruding theplastic earth at elevated pressure, drying the extruded earth, treatingthe dried earth with sulfuric acid in an amount sufficient only toneutralize the added sodium hydroxide, water washing the neutralizedearth to remove soluble salts, adjusting the water content of the washedearth tc a value between 52% to 56 extruding the washed earth atelevatedpressure, and dryiln-gtheextruded earth.

9. A process for improving the decolorizingef ficiency' of 'Georgia-l'l'orida type fullers earth, which comprises intimately mixing with theearth from 0.1% to 1.75% by weight of a water-soluble alkaline reagentand sufficient water togive a plastic earth containing from 45% to 60%'of 7 water, extruding the plastic earth at elevated pressure, dryingthe extruded earth, calcining the dried earth at 800 F. to 1200 treatingthe calcined earth with mineral acid in an amount suificient only toneutralize the added alkaline. reagent, water washing the neutralizedearth to remove soluble salts, and drying the washed'earth...

10. A process for improving the decolorizi'ngefficiency ofGeorgia-Florida type 'iullers earth, which comprises intimately mixingwith the earth 1% by weight of sodium hydroxide and sufficient water togive a plastic earth containing irom.5.2%f

to 56 of water, extruding the plastic earth at elevated pressure,dryingthe extruded earth, calcining the dried earth at 800 F. to 1200F.,-tr'eating the calcined earth with sulfuric acid in an amountsuflicient only to neutralize the added sodium hydroxide, water washingthe neutralized earth to remove soluble salts-wand drying the washedearth.

WILLIAM S. W. McCAR'I-ERZ;

REFERENCES 01th!) The following referenlces are of record in the file ofthis patent: I V

UNITED STATES PATENTS Name Date La- Lande Nov. 28, 1944 Number

